From 0b59cb7ce15f244a67837379a64b70a7b361cb16 Mon Sep 17 00:00:00 2001
From: Oscar Lafarga <otech47@gmail.com>
Date: Sat, 4 Mar 2023 12:49:44 +0000
Subject: [PATCH] Add test for decoding txn with oversized witness

---
 wire/msgtx_test.go | 68 ++++++++++++++++++++++++++++++++++++++++++----
 1 file changed, 63 insertions(+), 5 deletions(-)

diff --git a/wire/msgtx_test.go b/wire/msgtx_test.go
index bcbe025d4c..ea1846ab4b 100644
--- a/wire/msgtx_test.go
+++ b/wire/msgtx_test.go
@@ -831,7 +831,57 @@ func TestTxWitnessLimits(t *testing.T) {
 		return encodedTxnBuffer
 	}
 
+	var createTxnWithOversizedWitness = func() []byte {
+		var encodedTxnBuffer []byte
+
+		txnBeforeWitnessEncoded := []byte{
+			0x1, 0x0, 0x0, 0x0, // Version
+			TxFlagMarker, // Marker byte indicating 0 inputs, or a segwit encoded tx
+			WitnessFlag,  // Flag byte
+			0x1,          // Varint for number of inputs
+			0xa5, 0x33, 0x52, 0xd5, 0x13, 0x57, 0x66, 0xf0,
+			0x30, 0x76, 0x59, 0x74, 0x18, 0x26, 0x3d, 0xa2,
+			0xd9, 0xc9, 0x58, 0x31, 0x59, 0x68, 0xfe, 0xa8,
+			0x23, 0x52, 0x94, 0x67, 0x48, 0x1f, 0xf9, 0xcd, // Previous output hash
+			0x13, 0x0, 0x0, 0x0, // Little endian previous output index
+			0x0,                    // No sig script (this is a witness input)
+			0xff, 0xff, 0xff, 0xff, // Sequence
+			0x1,                                    // Varint for number of outputs
+			0xb, 0x7, 0x6, 0x0, 0x0, 0x0, 0x0, 0x0, // Output amount
+			0x16, // Varint for length of pk script
+			0x0,  // Version 0 witness program
+			0x14, // OP_DATA_20
+			0x9d, 0xda, 0xc6, 0xf3, 0x9d, 0x51, 0xe0, 0x39,
+			0x8e, 0x53, 0x2a, 0x22, 0xc4, 0x1b, 0xa1, 0x89,
+			0x40, 0x6a, 0x85, 0x23, // 20-byte pub key hash
+		}
+		// Add the number of items on the witness stack
+		witnessItemCountEncoded := []byte{
+			0x1, // 1 item on the witness stack
+		}
+		encodedTxnBuffer = append(
+			txnBeforeWitnessEncoded,
+			witnessItemCountEncoded...
+		)
+		// Add the size of the witness item
+		witnessLengthEncoded := []byte{
+			0xfe, 0x01, 0x09, 0x3d, 0x00, // 4,000,001 bytes
+		}
+		encodedTxnBuffer = append(encodedTxnBuffer, witnessLengthEncoded...)
+		// Add a witness item with 4,000,001 bytes of zeros
+		for i := uint(0); i < 4_000_001; i++ {
+			encodedTxnBuffer = append(encodedTxnBuffer, 0)
+		}
+		var locktimeEncoded = []byte{
+			0x0, 0x0, 0x0, 0x0, // Lock time
+		}
+		encodedTxnBuffer = append(encodedTxnBuffer, locktimeEncoded...)
+
+		return encodedTxnBuffer
+	}
+
 	encodedTxnWithManyWitnessItems := createTxnWithManyWitnessItems()
+	encodedTxnWithOversizedWitness := createTxnWithOversizedWitness()
 
 	tests := []struct {
 		buf     []byte          // Wire encoding
@@ -842,11 +892,19 @@ func TestTxWitnessLimits(t *testing.T) {
 	}{
 		// Transaction with 1 input and 4,000,001 items in the witness stack
 		{
-			encodedTxnWithManyWitnessItems,
-			pver,
-			WitnessEncoding,
-			txVer,
-			&MessageError{},
+			buf: encodedTxnWithManyWitnessItems,
+			pver: pver,
+			enc: WitnessEncoding,
+			version: txVer,
+			err: &MessageError{},
+		},
+		// Transaction with 1 input and a large witness script
+		{
+			buf: encodedTxnWithOversizedWitness,
+			pver: pver,
+			enc: WitnessEncoding,
+			version: txVer,
+			err: &MessageError{},
 		},
 	}